Plan cache

  • I recently inherited a vendor database and one of things I noticed was a daily maintenance job

    set to reconfigure maxdop before launching and then setting it back upon completion. I understand the logic behind this but I'm concerned about the cachestore flushes. Thoughts and suggestions appreciated.

    Configuration option 'affinity mask' changed from 0 to 0. Run the RECONFIGURE statement to install.

    Configuration option 'cost threshold for parallelism' changed from 50 to 10. Run the RECONFIGURE statement to install.

    Configuration option 'max degree of parallelism' changed from 6 to 0. Run the RECONFIGURE statement to install.

    SQL Server has encountered 1 occurrence(s) of cachestore flush for the 'Object Plans' cachestore (part of plan cache) due to some database maintenance or reconfigure operations.

    SQL Server has encountered 1 occurrence(s) of cachestore flush for the 'SQL Plans' cachestore (part of plan cache) due to some database maintenance or reconfigure operations.

    SQL Server has encountered 1 occurrence(s) of cachestore flush for the 'Bound Trees' cachestore (part of plan cache) due to some database maintenance or reconfigure operations.

  • Yeah, you're recompiling all the plans after that runs. It might not be that big a deal. It really depends on your system, the code, all sorts of factors. Also, it could be negatively impacting performance. I'd certainly gather wait statistics on the server to see if there's a spike there, how bad it is. Also look at CPU and queuing around it because of the compiles.

    "The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
    - Theodore Roosevelt

    Author of:
    SQL Server Execution Plans
    SQL Server Query Performance Tuning

  • Thank you

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